A head-up display (HUD) is a translucent display panel which may be used to present information to a user without requiring the user to divert his or her gaze from a preferred gaze direction. For example, a HUD may be used to present a driver of a vehicle with a variety of information (e.g., speed, fuel consumption, navigation information, time, etc.) while allowing the driver to simultaneously view traffic conditions and the road in front of the vehicle.
A typical HUD includes a combiner, a projector, and a visual data source. The combiner is a translucent panel upon which visual data is projected. The combiner usually includes one or more optical coatings that reflect only the specific wavelengths of monochromatic light which are projected by the HUD projector. Thus, the combiner can be conceptualized as a translucent mirror. The HUD projector is positioned relative to the combiner to allow images, graphics, video, or other visual data to be projected onto the combiner. The combiner then reflects the projected images toward the user.
HUD systems require careful design consideration to ensure reliable performance under a variety of operational conditions. For example, a HUD may be exposed to varying environmental conditions such as high humidity, extreme temperatures, and the presence of contaminants which may cause corrosion. Additionally, when a HUD is implemented in a mobile environment, it is desirable to protect the combiner when the HUD system is inactive to mitigate the potential of damaging the combiner. For this purpose, a positioning system may be used to move the combiner between an active display position and a protected storage position.
Repeatable positional accuracy is important for combiner positioning systems because an improperly positioned combiner will not function properly in a HUD system. Such positional accuracy may be achieved by using high precision parts which are manufactured and maintained to very close tolerances. However, the need for such close tolerances has the undesirable effect of increasing the manufacture and maintenance expense associated with the positioning system.
Further, failure to control vibration associated with the combiner may result in a display that is irritating to the user and unpleasant to view over extended periods. Thus, a positioning system is needed which allows the combiner to move between a protected position and a display position and which reduces undesirable vibration to allow for a pleasant viewing experience.